Sharath JAYAKUMAR
defended his PhD on 13 december 2024
“Hydrophobic ceramic capillary membranes applied to desalination and oil removal”
In front of the jury composed of:
– M. Wojciech KUJAWSKI, Professeur, Université Nicolas Copernicus de Torun, Pologne – Rapporteur
– Mme. Alice MIJA, Professeur, Université Côte d’Azur, Nice – Rapporteur
– M. Philippe TRENS, Professeur des Universités, ENSCM, Montpellier – Examinateur
– Mme. Marie-Alix PIZZOCCARO-ZILAMY, Maître de Conférences, Université de Twente, Pays-Bas – Examinateur
– M. Mihail BARBOIU, Directeur de recherche, CNRS, Montpellier – Directeur de thèse
– Mme. Sophie CERNEAUX, Maître de Conférences, ENSCM, Montpellier – Co-encadrante de thèse
Abstract:
One of the potential methods for the treatment of saline water is Membrane Distillation (MD). MD is a thermally driven separation process where the driving force is the difference of partial pressure across the membrane, which is induced by the temperature difference applied on both sides of the membrane. The feed solution is vaporized at the membrane interface, and the vapors pass through the membrane pores to condense on the cold side of the membrane as permeate. Only porous hydrophobic membranes can be used in the MD process, as the surface should be non-wetting and allow only vapors to pass through the membrane pores. Although polymeric membranes are widely studied in MD applications, ceramic membranes can be more advantageous due to their great mechanical strength, high chemical and thermal stability.
In this work, we fabricated capillary cordierite support by extrusion process. The supports were prepared with different pore-forming agents such as corn starch, maize flour, and rice husk to evidence their influence on the membrane support characteristics. The capillary support was coated with three filtration layers, each layer containing zirconia (8 m2/g), zirconia (43 m2/g) and γ-
alumina. Since the membrane had to be hydrophobic, the membrane surface was modified by grafting alkoxysilane groups containing 6, 8, and 12 carbon atoms in the alkyl chain. The filtration layers and the membrane morphology were observed by SEM; the structure of the raw powders was analyzed by XRD, and the mechanical strength of the membrane was determined using the 3-point bending method. The pore size of the support was determined by Mercury Porosimetry. The permeability of the hydrophilic membranes was between 100 and 1500 L m-2 h-1 bar-1, and the liquid entry pressure of water (LEPw) of the modified hydrophobic membranes was between 2 and 6 bar. Later, MD in Air Gap configuration was performed using NaCl solution as the feed at a concentration of 0.5 M to yield a salt rejection efficiency of 95 % for a temperature gradient of 80 °C. The membranes were also tested for oil-water emulsion separation and projected over 85 % rejection of oil. Additionally, hydrophilic tubular membranes were also coated with PVDF to induce hydrophobic properties and tested for oil-water emulsion filtration.
